1. Field
This application relates generally to wireless communication and more specifically, but not exclusively, to wireless network selection.
2. Introduction
A geographic area may be served by overlapping public land mobile networks (PLMNs) that provide mobile cellular services. For example, different wireless network operators may deploy different PLMNs throughout the same city. Under certain circumstances, a given access terminal (e.g., a cell phone) may be allowed to access these different PLMNs. Accordingly, such an access terminal may be configured to select which PLMN is to be used at a given point in time.
In some cases, an access terminal may employ an automatic mode of PLMN selection. Here, the access terminal may continually monitor for available PLMNs and automatically switch to a new PLMN based on specified selection criteria. In a typical case, the selection criteria comprise a prioritized list of PLMNs that indicates the order in which the access terminal is to select a PLMN in the event multiple PLMNs are available. Other types of selection criteria may be used as well. For example, priority may be given to a PLMN that would currently provide the best quality of service for the access terminal.
In some cases, an access terminal may employ a manual mode of PLMN selection. For example, a list of currently available PLMNs may be displayed on a screen of the access terminal. The user may then select one of the PLMNs and the access terminal switches to that PLMN. In contrast with an automatic PLMN selection mode, in this case the access terminal will stay on this PLMN even if other higher priority PLMNs are available. For example, the access terminal may stay on the selected PLMN until a different PLMN is manually selected or until the selected PLMN no longer provides service to the access terminal.
An access terminal also may be configured to enable a user to manually select a closed subscriber group (CSG) associated with one or more wireless cells (e.g., at least one access point). In the event the selected CSG is in a different PLMN than the current PLMN, a PLMN selection procedure may be invoked in response to the selection of the CSG. In such a case, the PLMN selection procedure may not provide a desirable result.
For example, an access terminal operating in automatic PLMN selection mode may not be able to remain camped on a selected CSG. This may be the case because the automatic PLMN selection mode may automatically switch to another PLMN based the designated selection criteria (e.g., if a background search procedure detects a higher priority PLMN).
In addition, an access terminal operating in manual PLMN selection mode may attempt to remain on the new serving PLMN even after the access terminal has left the coverage area of the selected CSG cell. In the event no suitable cell is found for the access terminal on that PLMN (e.g., the access terminal is not allowed to access any cell other than the cells of the selected CSG), the user will be without service. As a result, user interaction will be required to select another PLMN.